Exercise device



FIG. 1 shows a front view of the design.

FIG. 2 shows a back view of the design.

FIG. 3 shows a top view of the design.

FIG. 4 shows a bottom view of the design.

FIG. 5 shows a side view of the design; and,

FIG. 6 shows a perspective view of the design.

The portions in even broken lines are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for an exercise device, as shown and described. 